1. Technical Field
The present invention relates to liquid ejecting apparatuses that selectively eject multiple types of liquid onto a print medium from a head that moves back and forth in the main scanning direction, and particularly relates to techniques for preventing the occurrence of darkness unevenness caused by changes in the order in which liquids are superimposed upon the print medium in the inbound and outbound passes of the head.
2. Related Art
The ink jet printer disclosed in, for example, JP-A-8-156286 is known as a color ink jet printer that prevents the occurrence of darkness unevenness resulting from inverting the order in which inks are superimposed upon recording paper in the outbound and inbound passes of a recording head during bidirectional recording.
In this ink jet printer, a multi-nozzle ink jet print head for each of its multiple colors, which has a scanning width W, is supported on a carriage using a step-shaped support platform so that the multi-nozzle ink jet print head for each of its multiple colors is disposed being skewed relative to each other by a predetermined pitch P (W<P<2W) in the sub scanning direction. Through such a configuration, the borders of the band regions scanned by the multi-nozzle ink jet print head for each of its multiple colors do not overlap and the multiple colors in the multi-nozzle ink jet print head for each of its multiple colors always scan on recording paper in the same order both when the carriage is outbound and when the carriage is inbound; as a result, the appearance of banding caused by recording paper feed errors and so on can be reduced, and the occurrence of banding caused by inverting the order in which the ink is superimposed upon the recording paper when the carriage is outbound and when the carriage is inbound can be prevented.
However, in the stated past ink jet printer, it is necessary to dispose the multi-nozzle ink jet print head for each of its multiple colors, which has a scanning width W, being skewed from each other by the predetermined pitch P (W<P<2W) in the sub scanning direction. Accordingly, the size of the recording head is greater compared to, for example, the case where the multiple colors in the multi-nozzle ink jet heads for each of its multiple colors are arranged in a row in the main scanning direction.
Furthermore, it is necessary to provide a separate support platform for disposing the multi-nozzle ink jet print head for each of its multiple colors according to the aforementioned positional relationships, which increases the cost.